1. Field of the Invention
The present invention relates to dampening masks for use in aircraft, and more paticularly to dampening masks having a function or absorbing moisture contained in breath exhaled through a human nose or mouth and, during inhalation, dampening inhaled breath by giving off the previously absorbed moisture.
2. Description of the Related Art
It is generally known that the air within aircraft is very dry. This is because the outside air temperature at high altitudes at which the aircraft flies is very low, typically -40.degree. C. to -70.degree. C., and thus the outside air taken into the inner space of te aircraft is very dry. Generally, however, the aircraft is not provided with any dampening devices, because such devices will add to the weight of the aircraft and will further cause ill effects, such as condensed water on the cold inner walls of the aircraft or icing and water contamination. Excessively dried air in the aircraft is not preferable for the passengers and crew, and will actually cause several environmental problems particularly during a long flight of about two or more hours. For example, travelers will frequently feel sensations of stimulus, pain or displeasure in the mucous membranses of the nose and the mout when respiring such extremely dried air. Such problems which occur in connection with the respiration of extremely dry air in aircraft will sometimes cause significant pain or displeasure particularly during sleep unless the respired air is moderately humid, because the vital dampening function performed in the nose is weakened during sleep. This is pointed out in the SAE report AIR1609 (Apr. 30, 1982), United States Automobile Engineering Association, for example.
In view of the foregoing problems, it is desired to improve the environment for persons in aircraft. However, it is not practical to dampen the air within the aircraft to solve the above problems. So, it is difficult to improve the environment in the aircraft and any simple and effective means for doing so has of yet not been proposed.
The inventors studied and developed various subjects in attempts to achieve advances in the above-described problems, and eventually came to note the following facts:
Human respiration is a series of repeated actions of exhaling and inhaling. Generally, the relative humidity of exhaled breath is almost 100%. Therefore, when respiration is performed in extremly dry air such as that in aircraft, the moisture contained in the exhaled breath is dispersed in the air in the aircraft while extremely dry air is inhaled through the nose or mouth. The continuation of respiration in such an environment causes the previously mentioned significant pair or displeasure.
In view of the foregoing, the inventors thought that if there is some means which would allow man to temporarily retain moisture contained in exhaled breath without dispersing such moisture into the air and would further allow man to inhale such retained moisture together with air, then such means would be an effective measure to solve he above-mentioned problems.
Japanese Patent Publication No. 20557/1971 discloses an idea relying on the nature of inhaled and exhaled breath and proposes a mask of the type having fibers wound on heat exchangers made of aluminum, for example, the fibers being capable of absorbing moisture well, for the purposes of warming cold inhaled breath of imparting the temporarily absorbed moisture to the inhaled breath. The proposed mask, however, works depending on substantial temperature differences between the exhaled breath (at body temperature) and the outside air temperature, and cannot function well in an environment such as that in aircraft where the air is conditioned to a suitable temperature (usually, 23.degree. to 26.degree. C.).